From 305ef69d5878ecaf1b9655e7899d663290f53af5 Mon Sep 17 00:00:00 2001 From: weiting-cn <2254912@qq.com> Date: Fri, 11 Feb 2022 16:09:17 +0800 Subject: [PATCH 1/4] =?UTF-8?q?=E6=9B=B4=E6=96=B0=EF=BC=9A0015.=E4=B8=89?= =?UTF-8?q?=E6=95=B0=E4=B9=8B=E5=92=8C=EF=BC=8C0018.=E5=9B=9B=E6=95=B0?= =?UTF-8?q?=E4=B9=8B=E5=92=8C=EF=BC=88=E5=8E=BB=E9=87=8D=E4=BC=98=E5=8C=96?= =?UTF-8?q?=EF=BC=89?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0015.三数之和.md | 4 ++++ problems/0018.四数之和.md | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/problems/0015.三数之和.md b/problems/0015.三数之和.md index e191eabc..9b59e66d 100644 --- a/problems/0015.三数之和.md +++ b/problems/0015.三数之和.md @@ -138,8 +138,12 @@ public: */ if (nums[i] + nums[left] + nums[right] > 0) { right--; + // 当前元素不合适了，可以去重 + while (left < right && nums[right] == nums[right + 1]) right--; } else if (nums[i] + nums[left] + nums[right] < 0) { left++; + // 不合适，去重 + while (left < right && nums[left] == nums[left - 1]) left++; } else { result.push_back(vector{nums[i], nums[left], nums[right]}); // 去重逻辑应该放在找到一个三元组之后 diff --git a/problems/0018.四数之和.md b/problems/0018.四数之和.md index bad258c1..c6c55d50 100644 --- a/problems/0018.四数之和.md +++ b/problems/0018.四数之和.md @@ -91,9 +91,13 @@ public: // nums[k] + nums[i] + nums[left] + nums[right] > target 会溢出 if (nums[k] + nums[i] > target - (nums[left] + nums[right])) { right--; + // 当前元素不合适了，可以去重 + while (left < right && nums[right] == nums[right + 1]) right--; // nums[k] + nums[i] + nums[left] + nums[right] < target 会溢出 } else if (nums[k] + nums[i] < target - (nums[left] + nums[right])) { left++; + // 不合适，去重 + while (left < right && nums[left] == nums[left - 1]) left++; } else { result.push_back(vector{nums[k], nums[i], nums[left], nums[right]}); // 去重逻辑应该放在找到一个四元组之后 From 65a341bf365eb3b2648c357a7a311a59ec6e9e18 Mon Sep 17 00:00:00 2001 From: Larry Liu Date: Fri, 11 Feb 2022 20:24:45 +0800 Subject: [PATCH 2/4] =?UTF-8?q?Update=20=E5=B9=BF=E5=B7=9E=E4=BA=92?= =?UTF-8?q?=E8=81=94=E7=BD=91=E5=85=AC=E5=8F=B8=E6=80=BB=E7=BB=93.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 字节跳动有广州研发岗位 --- problems/前序/广州互联网公司总结.md | 1 + 1 file changed, 1 insertion(+) diff --git a/problems/前序/广州互联网公司总结.md b/problems/前序/广州互联网公司总结.md index ae41c899..ac70f40c 100644 --- a/problems/前序/广州互联网公司总结.md +++ b/problems/前序/广州互联网公司总结.md @@ -14,6 +14,7 @@ ## 一线互联网 * 微信（总部） 有点难进！ +* 字节跳动（广州） ## 二线 * 网易（总部）主要是游戏 From 961ae6eadf6359f2ef6b787ad612475e02e6842e Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Fri, 11 Feb 2022 21:52:36 +0800 Subject: [PATCH 3/4] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880112.=E8=B7=AF?= =?UTF-8?q?=E5=BE=84=E6=80=BB=E5=92=8C.md=EF=BC=89=EF=BC=9A=E5=A2=9E?= =?UTF-8?q?=E5=8A=A0typescript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0112.路径总和.md | 89 +++++++++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) diff --git a/problems/0112.路径总和.md b/problems/0112.路径总和.md index 5ec8ffd0..de6caef0 100644 --- a/problems/0112.路径总和.md +++ b/problems/0112.路径总和.md @@ -766,11 +766,100 @@ let pathSum = function(root, targetSum) { }; ``` +## TypeScript + +> 0112.路径总和 + +**递归法：** + +```typescript +function hasPathSum(root: TreeNode | null, targetSum: number): boolean { + function recur(node: TreeNode, sum: number): boolean { + console.log(sum); + if ( + node.left === null && + node.right === null && + sum === 0 + ) return true; + if (node.left !== null) { + sum -= node.left.val; + if (recur(node.left, sum) === true) return true; + sum += node.left.val; + } + if (node.right !== null) { + sum -= node.right.val; + if (recur(node.right, sum) === true) return true; + sum += node.right.val; + } + return false; + } + if (root === null) return false; + return recur(root, targetSum - root.val); +}; +``` + +**递归法（精简版）：** + +```typescript +function hasPathSum(root: TreeNode | null, targetSum: number): boolean { + if (root === null) return false; + targetSum -= root.val; + if ( + root.left === null && + root.right === null && + targetSum === 0 + ) return true; + return hasPathSum(root.left, targetSum) || + hasPathSum(root.right, targetSum); +}; +``` + +**迭代法：** + +```typescript +function hasPathSum(root: TreeNode | null, targetSum: number): boolean { + type Pair = { + node: TreeNode, // 当前节点 + sum: number // 根节点到当前节点的路径数值总和 + } + + const helperStack: Pair[] = []; + if (root !== null) helperStack.push({ node: root, sum: root.val }); + let tempPair: Pair; + while (helperStack.length > 0) { + tempPair = helperStack.pop()!; + if ( + tempPair.node.left === null && + tempPair.node.right === null && + tempPair.sum === targetSum + ) return true; + if (tempPair.node.right !== null) { + helperStack.push({ + node: tempPair.node.right, + sum: tempPair.sum + tempPair.node.right.val + }); + } + if (tempPair.node.left !== null) { + helperStack.push({ + node: tempPair.node.left, + sum: tempPair.sum + tempPair.node.left.val + }); + } + } + return false; +}; +``` + +> 0112.路径总和 ii + + + ## Swift 0112.路径总和 **递归** + ```swift func hasPathSum(_ root: TreeNode?, _ targetSum: Int) -> Bool { guard let root = root else { From fde074cb2ab400b44707c178139d7757541bbf39 Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Fri, 11 Feb 2022 23:28:30 +0800 Subject: [PATCH 4/4] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880112.=E8=B7=AF?= =?UTF-8?q?=E5=BE=84=E6=80=BB=E5=92=8C=20ii=EF=BC=89=EF=BC=9A=E5=A2=9E?= =?UTF-8?q?=E5=8A=A0typescript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0112.路径总和.md | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/problems/0112.路径总和.md b/problems/0112.路径总和.md index de6caef0..2e10d98d 100644 --- a/problems/0112.路径总和.md +++ b/problems/0112.路径总和.md @@ -852,7 +852,39 @@ function hasPathSum(root: TreeNode | null, targetSum: number): boolean { > 0112.路径总和 ii +**递归法：** +```typescript +function pathSum(root: TreeNode | null, targetSum: number): number[][] { + function recur(node: TreeNode, sumGap: number, routeArr: number[]): void { + if ( + node.left === null && + node.right === null && + sumGap === 0 + ) resArr.push([...routeArr]); + if (node.left !== null) { + sumGap -= node.left.val; + routeArr.push(node.left.val); + recur(node.left, sumGap, routeArr); + sumGap += node.left.val; + routeArr.pop(); + } + if (node.right !== null) { + sumGap -= node.right.val; + routeArr.push(node.right.val); + recur(node.right, sumGap, routeArr); + sumGap += node.right.val; + routeArr.pop(); + } + } + const resArr: number[][] = []; + if (root === null) return resArr; + const routeArr: number[] = []; + routeArr.push(root.val); + recur(root, targetSum - root.val, routeArr); + return resArr; +}; +``` ## Swift